Well you can lock focus the way you describe it and start recording and focus will remain locked, until you want to change focus again (while recording). That's just not possible. Would it be possible for Panasonic to add "push AF" functionality through a firmware update? Maybe together with having the focus assist as an option while recording?
In menu:
Focus assist when using push AF: on or off
Focus assist in MF mode while recording: on or off
Actually I'd like a menu setting to have the front shutter trigger to only do re-focusing when pressed in Creative Movie Mode and the back recording button to start-stop recordings - that's what it's there for, right? I've both started and stopped recordings accidentally when all I was trying to do was half-press the trigger for re-focus.
I'm not liking the placement of the video button myself only because I will seem to hit it with my thumb when I am using the aperture wheel. I still recommend just using MF all the time even after the firmware update. It does find focus much better in low light but I just like the control of MF. Only problem is it can be a pain in the ol' arss trying to get a focus in low light even in MF with the focus assist. Sometimes it's best to turn off focus assist in certain situations because you lose your placement zoomed in so close and it makes it hard to find an edge to get a focus going. This is why I would love HDMI out, of course besides having that sweet signal going to a flash recorder.
I agree that MF is better, I would never using it during recording, but sometimes AF can be a handy tool. But what I will do asap is make a focus handle to attach to my lens, probably with some scale. I think for simple focusing a follow focus system is overkill.